A leading global business group has issued a ''corruption index'' for African countries, but corporate governance watchdogs say the World Economic Forum (WEF) ignored the role that its members play in corrupting poor countries. The rankings released last Tuesday by the Geneva-based WEF, known for its high-profile annual meetings in the alpine resort of Davos, Switzerland that attract the world's corporate and political luminaries, show Botswana leading the 21 African nations ranked for the quality of their public institutions.